There are several types of fuel cells. The transportable kind that comsume either pure H2 or an alcohol such as methanol will have a fuel cell body and membrane that is most likely made of a sulfonated perfluorocarbon type plastic. The perflourocarbon that is similar to what "GoreTex" relies on to exclude water but let water vapor pass. Polyvinylidene flouride is one of the perflourcarbons that midght be incorporated into a fuel cell for example. Selected for temperature and corrosion resistance (among other properties) its no doubt that fuel cell components such as these are almost immutable under ambient conditions and probably will never biodegrade. That's the bad news. The gOod news is that fuel "cell" walls are "doped" with noble metal catalysts that are very expensive and that the polymers themselves are orders of magnitude more costly than the sort that ordinary consumer goods are made with. Both can theoretically be recyclced in a closed loop, unless contaminated in some unforseen manner. The important thing for designers to look at in this early stage of fuel cell commercialization is ease of disassembly. FI the cell walls and membranes can be cost effectively removed from the rest of the product recycling is likely to happen. If its force fit in or otherwise stuck in a larger assembly, its destiny will be as "fluff" to the landfill or incinerator. This is more important than mere material selection.